Joint for metal tubes



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JOINT FOR METAL TUBES Filed Oct. 25, 1944 INVENTOR. 92: C5007,

Patented July 8, 1947 JOINT FOR METAL TUBES Earl C. Booth, Columbus, Ind., assignor to Noblitt- Sparks Industries, Inc., Columbus, Ind., a corporation of Indiana Application October 23, 1944, Serial No. 559,911

My invention relates to metal furniture and more particularly to that type of metal furniture embodying tubular structural elements. It is the object of my invention to produce a joint structure for use between two telescopically associated pieces of tubing, which structure will provide a firm and positive interconnection, will be of attractive appearance, and can be manufactured simply and economically. Another object of my invention is to produce a chair in which the back and lower portion of the chair are removably associated through the medium of telescopic joints.

In carrying out 'my invention, I collapse one end of one of the two tubes which are to be telescopically associated, and I shape the collapsed portion in cross-section so that it will fit against the inner surface of the 'other tube. The collapsed portion of the one tube is then inserted into the other, and the two tubes are secured together as by means of a transversely extending bolt. Where it is desired to prevent relative rotation of the two tubes, a portion of the outer tube may be offset inwardly to engage the side edges of the collapsed portion of the other tube. In embodying a joint of this kind in a chair, I provide for the chair-seat a support formed of tubing including portions extending rearwardly at the sides of the seat. I provide for the back a support which includes a piece of tubing terminating in portions which extend forwardly for telescopic association with the rearwardly extending portions of the seat-support. The telescopically associated tubes ar joined together by a joint of the character previously described.

The accompanying drawing illustrates my invention: Figs. 1 and 2 are side and front elevations, respectively, of a chair embodying my invention; Fig. 3 is a substantially horizontal section on the line 3-3 of Fig. 1; Fig. 4 is a transverse vertical section on the line 4-4 of Fig. 3; Fig. 5 is an axial section through a modified form of joint; and Figs. 6 and 7 are sections on the lines 6-6 and |-1 of Fig. 5.

The chair shown in the drawing embodies a sheet-metal seat Ill supported by a length f metal tubing bent to provide a transverse intermediate stretch ll, lower horizontal stretches l2, generally vertical stretches l3, and upper horizontal stretches l4 extending rearwardly along the sides of the seat In and secured thereto asby means of screw or bolts IS. The chairback I6 is conveniently formed of sheet-metal and is supported by a length of tubing I! which extends across the top and. down. the sides. O the 12 Claims. (Cl. 287-119) back and terminates in two forwardly projecting portions l8 telescopically associated with the 7 rear ends of the stretches 14 of the seat-support.

The preferred form of joint between the tube portions 14 and I8 is illustrated in Figs. 3 and 4. As shown in those figures, the tubes forming the two supports are of the same diameter. Each end of the tube l8 is collapsed to form a wall 20 of double thickness, and such wall is formed into a channel-like cross-section such that its outer surface will conform in curvature to the inner surface of the tube-portion l4. Desirably, the forming of the end of the tube 18 is so effected as to create a rather well-define shoulder 2| which, by engaging the end of-the tube I4, will positively limit inward movement of the tubeend [8, For the purpose of holding the two telescopically associated tubes together, I employ a bolt 22 which extends diametrically across the tube l4 and through the center of the collapsed portion 20 of the tube-end l8.

In manufacturing the chair described, the back and back-support are assembled separately from the seat and seat-support. As will be obvious, the two sub-assemblies may be nested for storage and shipment, thus conservin space. When the chair is to be erected, the collapsed ends l8 of the back-support are inserted into the stretches IA of the seat-support, and the bolts 22 then put in place and tightened. Because the two tubes are of the same diameter, and because of the shoulder 2|, the joint is relatively inconspicuous.

To impart extra strength and resilience to th telescopic joint and to prevent any relative rotation of the telescopically associated tubes, a portion of the wall of the tube I4 may be ofiset inwardly to engage the side edges of the collapsed portion 20 of the tube 18, as indicated at 23 in Fig. 4. If this construction is employed, the bolt 22 is desirably located at the offset portion in the tube l4, and a washer 24 conforming to the shape of the ofiset portion is inserted between the offset portion and the nut 25 of the bolt 22. This construction not only provides great strength and rigidity, but also permits the nut an ad acent end of the bolt 22 to be located within the bound ary of the outer surface of the tube M.

In the modified form of joint illustrated in Figs. 5, 6, and '7, the end of a tube 30 which is to be telescopically received within another tube 3| is collapsed and the collapsed portion formed into a channel section as indicated at 32 in Fig. 6. The end of the channel-shaped portion 32 is then curved further in cross-section to bring it into the f rm of a double-walled, circular tube, as indicated at 33. Desirably, the change in form from channel-section 32 to tubular section 33 is relatively abrupt so as to create a shoulder 34 against which one end of the outer tube 3! may rest.

Instead of securing the tubes 30 and 3| together by a transverse bolt as in the case of the joint previously described, I have illustrated another arrangement in Fig. 5. As will be clear from that figure, the end of the tubular section 33 is tapped for the reception of a screw 35. A washer 36 interposed between the head of the screw 35 and the end of the tube 3| prevents withdrawal of the double-walled tubular portion 33 from its seat in the tube 31, while movement of the tubular portion 33 in the opposite direction is limited by the shoulder 34. The joint illustrated in Figs. 5, 6, and 7 may be used where relative rotation of the two telescopically associated tubes about their common axis is desired.

I claim as my invention:

1. In combination, a metal tube having one end collapsed to form a single wall of double thickness, said wall of double thickness being curved transversely, a second tube of substantially the same diameter as the first tube, the outer surface of said collapsed portion. substantially conforming in curvature to and engaging the inner surface of the second tube for an angular extent of more than 180, and means for securing the two tubes together withthe collapsed portion of the first tube disposed within the second tube.

2. In combination, a metal tube having one end collapsed to form a single wall of double thickness, said wall of double thickness being curved transversely, a second tube, the outer surface of said collapsed portion substantially conforming in curvature to and engaging the inner surface of the second tube for an angular extent of more than 180, and means for securing the two.

tubes together with the collapsed portion of the first tube disposed within the second tube.

3. In combination, a metal tube having one end collapsed to form a single wall of double thickness, said wall of double thickness being curved transversely, a second tube of substantially the same diameter as the first tube, the outer surface of said collapsed portion substantially conforming in curvature to and engaging the inner surface of the second tube for an angular extent of more than 180,, and a bolt extending transversely through said second tube and also through said collapsed portion.

4. In combination, a metal tube having one end collapsed to form a single wall of double thickness, said wall of double thickness being curved transversely, a second tube, the outer surface of said collapsed portion substantially conforming in curvature to and engaging the inner surface of the second tube for an angular extent of more than 180, and a bolt extending transversely through said second tube and also through said collapsed portion.

5. The invention set forth in claim 1 with the addition. that said collapsed portion is of channel section, a portion of the wall of said second tube being offset inwardly to engage the edges of the collapsed portion.

6. The invention set forth in claim 1 with the addition that said collapsed portion is of channel section, a portion of the wall of said second tube 4 being offset inwardly to engage at least one edge of the collapsed portion.

7. The invention set forth in claim 1 with the addition that said collapsed portion is of channel section, a portion of the wall of said second tube being offset inwardly to engage the edges of the collapsed portion, said means comprising a bolt extending through said second tube at said offset portion, said bolt being provided with a washer conforming in shape to the outer surface of said offset portion.

8. The invention set forth in claim 1 with the addition that said collapsed portion is of channel section; a portion of the wall of said second tube being offset inwardly to engage the edges of the collapsed portion, said means comprising a bolt extending through said second tube at said offset portion.

9. In combination, a metal tube having one end collapsed to form a single wall of double thickness, said wall of double thickness being curved transversely, amember having a circular opening, the outer surface of said collapsed portion substantially conforming in curvature to and engaging the inner surface of said opening for an angular extent of more than and means for securing the tube and member together with said collapsed portion within said opening.

10. The invention set forth in claim 9 with the addition that said collapsed portion is curved transversely into a substantially complete tubular section, a washer overlying said member, and a screw extending through said washer and axially into the double-thickness tubular portion of said tube.

11. In combination, a metal tube having one end collapsed to form a single wall of double thickness, said Wall of double thickness being curved transversely, a second tube of substantially the same diameter as the first tube, the outer surface of said collapsed portion substan-- tially conforming in curvature to and engaging the inner surface of the second tube, for an angular extent of more than 180.

12. In combination, a metal tube having one end collapsed to form a single wall of double thickness, said wall of double thickness being curved transversely, a member having a circular opening, the outer surface of said collapsed portion substantially conforming in curvature to and engaging the inner surface of said opening, for an angular extent of more than 180.

EARL C. BOOTH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,350,582 Booth June 6, 1944 2,071,084 Nolan Feb. 16,1937 2,303,039 Gilkison Nov. 24, 1942 2,346,449 Noblitt et a1 Apr. 11, 1944 FOREIGN PATENTS Number Country Date 76,826 Sweden Dec. 24, 1931 509,492 Germany Feb. 15, 1935 451,909 Great Britain Aug. 13, 1936 

